Seal for use with medical device and system

ABSTRACT

A seal adapted for use with medical devices is provided. The medical device may be a lead having a distal tip adapted for implantation on or about the heart and for connection to a system for monitoring or stimulating cardiac activity. The lead assembly in one embodiment includes an atraumatic tip. A seal is provided within the lead tip assembly, which prevents or limits further entry of fluids through the lead tip. The lead may be a left ventricular lead with a hemostasis mechanism provided therewithin.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is related to U.S. patent application Ser. No.09/133,310 filed Aug. 12, 1998, entitled “EXPANDABLE SEAL FOR USE WITHMEDICAL DEVICE AND SYSTEM”, which is incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention relates generally to medical devices, suchas leads and catheters. More particularly, it pertains to seals orhemostasis mechanisms for medical devices such as leads and catheters.

BACKGROUND OF THE INVENTION

[0003] Leads implanted in or about the heart have been used to reverse(i.e., defibrillate or cardiovert) certain life threatening arrhythmias,or to stimulate contraction (pacing) of the heart. Electrical energy isapplied to the heart via the leads to return the heart to normal rhythm.Leads have also been used to sense in the atrium or ventricle of theheart and to deliver pacing pulses to the atrium or ventricle. The samelead used to sense the condition is sometimes also used in the processof delivering a corrective pulse or signal from the pulse generator ofthe pacemaker.

[0004] Cardiac pacing may be performed by the transvenous method or byleads implanted directly onto the ventricular epicardium. Most commonly,permanent transvenous pacing is performed using a lead positioned withinone or more chambers of the heart. A lead, sometimes referred to as acatheter, may be positioned in the right ventricle or in the rightatrium through a subclavian vein, and the lead terminal pins areattached to a pacemaker, which is implanted subcutaneously. The lead mayalso be positioned in both chambers, depending on the lead, as when alead passes through the atrium to the ventricle. Pacing and sensingelectrodes may be positioned within the atrium or the ventricle of theheart.

[0005] Pacemaker leads represent the electrical link between the pulsegenerator and the heart tissue, which is to be excited. These pacemakerleads include single or multiconductor coils of insulated wire having aninsulating sheath. The coils provide a cylindrical envelope, many timesreferred to as a lumen, which provides a space into which a stiffeningstylet or guidewire can be inserted. The conductive coil is connected toan electrode in an electrode assembly at a distal end of the lead.

[0006] During use, the lead conducts critical information to and fromthe heart. The lead, therefore, must remain in sufficient operativecondition without interference from entry of bodily fluids. A lumen usedas a means for deployment must remain free of blood to remainfunctional. Clotting blood hampers maneuverability. In addition, bloodin the lumen could cause corrosion. To prevent entry of bodily fluidsinto the lead, a seal can be provided at the distal end of the lead.Conventional leads do not have open ends, i.e. the lumens thereof areclosed. Leads which have moving parts, such as retractable fixationparts for example, use O-ring type seals to seal the distal end of thelead from entry of bodily fluids. The O-ring seals can be difficult tomanufacture due to dimensional constraints which affect theeffectiveness of the seal and the ease with which parts move.

[0007] Accordingly, there is a need for a lead, which is sufficientlysealed from the environment. There is also a need for a reliable meansfor performing cardiac sensing and pacing of the left atrium orventricle, with a lead which is sufficiently sealed from theenvironment.

SUMMARY OF THE INVENTION

[0008] In one embodiment, a body-implantable lead assembly is providedcomprising a lead, one end being adapted to be connected to anelectrical supply for providing or receiving electrical pulses. The leadfurther comprises a distal tip, which is adapted to be atraumatic. Thelead also has a sheath of material inert to body materials and fluidsand at least one conductor extending through the lead body. The lead hasa distal electrode adapted for implantation proximate to or within theheart while connected with a system for monitoring or stimulatingcardiac activity. The lead, however, is not limited to use in thecoronary vascular system.

[0009] In one embodiment a distal tip electrode is provided which isadapted for implantation proximate to the heart, the electrode beingconnected with a system for monitoring or stimulating cardiac activity.

[0010] The lead includes a seal or hemostasis mechanism. The terms“seal”, “seal mechanism” and “hemostasis mechanism” may be usedinterchangeably in describing the present invention. The seal can be inthe form of a polymer membrane located at the distal or proximal end ofthe lead.

[0011] In one embodiment, the provided medical device includes anelectrode tip, supplies a stylet for placement of the lead, which issealed from exposure to fluids. The lead avoids deterioration of itsfunction due to entry of liquid inside the lead, owing to the provisionof a highly effective seal. In addition, the seal remains functionalwhen the lead is removed for short periods of time from an environmentfilled or partially filled with fluid.

[0012] The present invention provides a lead, which may be positioned inor on the left ventricle to perform cardiac pacing. In one embodimentthe present invention contemplates all types of over the wire leadswhich have an open distal end, which may be positioned in or on the leftchambers of the heart for use in sensing and pacing, and/or “shocking”or cardioverting. The present invention is directed to left ventricularleads providing a hemostasis mechanism or seal in the lead lumen. It hasbeen discovered that a left ventricular lead deployed over a guide wireinto the coronary venous system is easily maneuvered into a desiredpacing site. It has also been discovered that when the vasculature isunusually difficult or the procedure requires more time, blood canmigrate into the lead lumen and begin to coagulate. This can cause unduefriction between the lead and the guide wire, interfering with themaneuverability of the lead. Accordingly, the present invention providesan over the wire left ventricular lead having a hemostasis mechanism orseal, which preempts blood from entering the lead lumen.

[0013] In another embodiment, a hemostasis mechanism for leftventricular leads is provided which comprises a polymer membrane at theproximal or distal end of the lead. The membrane may be a cusp valvemade of a suitable biocompatible polymer. In another embodiment, thehemostasis mechanism may be removable and disposable. This embodimentmay be removably attached to the terminal pin of the left ventricularlead. In another embodiment, a grommet attachment to the terminal pin incombination with a hemostasis valve which permits the passage of theguide wire and a port for introduction of fluid are provided. Thepresent invention also contemplates the use of the leads and sealsdisclosed herein as left ventricular leads.

[0014] These and other embodiments, aspects, advantages, and features ofthe present invention will be set forth in part in the description whichfollows, and in part will become apparent to those skilled in the art byreference to the following description of the invention and referenceddrawings or by practice of the invention. The aspects, advantages, andfeatures of the invention are realized and attained by means of theinstrumentalities, procedures, and combinations particularly pointed outin the appended claims and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is a side elevational view illustrating a lead constructedin accordance with one embodiment.

[0016]FIG. 2 is a cross-sectional view illustrating a system fordelivering signals to the heart constructed in accordance with oneembodiment.

[0017]FIG. 3A is a cross-sectional view of the distal portion of an overthe wire left ventricular lead for monitoring and stimulating the heartconstructed in accordance with one embodiment.

[0018]FIG. 3B is a cross-sectional view of the proximal portion of anover the wire left ventricular lead for monitoring and stimulating theheart constructed in accordance with one embodiment.

[0019]FIG. 3C is a cross-sectional view of the distal portion of an overthe wire left ventricular lead for monitoring and stimulating the heartconstructed in accordance with one embodiment.

[0020]FIG. 3D is a cross-sectional view of the distal portion of an overthe wire left ventricular lead for monitoring and stimulating the heartconstructed in accordance with one embodiment.

[0021]FIG. 4 is an end view of a hemostasis mechanism as shown in FIGS.3A-3D, showing an alternative embodiment of a valve.

[0022]FIG. 5 is an end view of a hemostasis mechanism as shown in FIGS.3A-3D, showing an alternative embodiment of a valve.

[0023]FIG. 6 is an end view of a hemostasis mechanism as shown in FIGS.3A-3D, showing an alternative embodiment of a valve.

[0024]FIG. 7 is a cross-sectional view of the proximal portion of anover the wire left ventricular lead for monitoring and stimulating theheart constructed in accordance with one embodiment.

[0025]FIG. 8 is a distal end view of a lead seal as shown in FIG. 7.

[0026]FIG. 9 is a cross-sectional view of the proximal portion of anover the wire left ventricular lead for monitoring and stimulating theheart constructed in accordance with one embodiment.

DESCRIPTION OF THE EMBODIMENTS

[0027] In the following detailed description, reference is made to theaccompanying drawings which form a part hereof, and in which is shown byway of illustration specific embodiments in which the invention may bepracticed. These embodiments are described in sufficient detail toenable those skilled in the art to practice the invention, and it is tobe understood that other embodiments may be utilized and that structuralchanges may be made without departing from the spirit and scope of thepresent invention. Therefore, the following detailed description is notto be taken in a limiting sense, and the scope of the present inventionis defined by the appended claims and their equivalents.

[0028] One embodiment of a lead 10 is illustrated in FIG. 1. The lead 10comprises a lead body 11, and extends from a proximal end 32 to a distalend 30. An elongate conductor is contained within the lead body 11, anda lead tip 20 is disposed within the distal end 30. The lead tip 20comprises an open lumen lead tip. The stylet 14 stiffens the lead 10,and can be manipulated to introduce an appropriate curvature to the lead10, facilitating the insertion of the lead 10 into and through a veinand through an intracardiac valve to advance the distal end 30 of thelead 10 into the heart, for example into the right ventricle of theheart. A stylet knob 12 is coupled with the stylet 14 for rotating thestylet 14 and advancing the lead 10.

[0029]FIG. 2 illustrates another embodiment, showing a view of a lead200 adapted for delivering electrical pulses to stimulate the heart. Thelead 200 is not limited to any particular type of lead, but in apreferred embodiment the lead is an open lumen lead, i.e. a lead havinga lumen open at its distal end. The lead 200 extends from a proximal end202, which is adapted to connect with equipment which supplieselectrical pulses, to a distal end 204 which is adapted to be insertedinto the heart. Proximate to the distal end 204 is an electrode tip 230.The electrode tip 230 includes a seal (FIG. 3A or 3B) disposed thereinto preempt bodily fluid from entering through the electrode tip 230.

[0030] A connector terminal 210 is disposed near the proximal end 202 ofthe lead 200. The connector terminal 210 electrically connects thevarious electrodes and conductors within the lead 200 to a pulse sensorand signal generator 240. The pulse sensor and signal generator 240contains electronics to sense various electrical signals of the heartand also produce electrical pulses for delivery to the heart, dependingon the type of lead 200 used. The pulse sensor and signal generator 240also contains electronics and software necessary to detect certain typesof arrhythmias and to correct for them. The lead terminal connector 210provides for the electrical connection between the lead 200 and thepulse sensor and signal generator 240.

[0031] Referring to FIGS. 3A-3D and 4-6, a hemostasis mechanism forleads, for example left ventricular leads, is shown. The hemostasismechanism as described herein is used to prevent body fluids frommigrating into the lumen of a left ventricular lead during and afterdeployment into the coronary vascular system. The hemostasis mechanismsdescribed herein apply to sealing the internal lumen of a lead implantedin the heart but are not intended to be limited to that application.

[0032] The embodiments illustrated in FIGS. 3A-3D and 4-6 are directedto over the wire left ventricular leads with hemostasis mechanisms topreempt blood from entering the lead lumen, thus maintaining thesuperior maneuvering capabilities of the over the wire left ventricularlead.

[0033] Illustrated in FIG. 3A is a lead 300 wherein a hemostasismechanism 320 is provided. The lead 300 is adapted to be implanted in,on, or around the heart. The lead 300 can comprise a number ofconfigurations such as, although not limited to, those described aboveand shown in the Figures, for instance the leads shown in FIGS. 1 and 2.The hemostasis mechanism of the present invention may be utilized with alead as set forth in U.S. Pat. No. 5,755,766, incorporated herein byreference.

[0034] As shown at FIG. 3A, lead 300 is an over the wire leftventricular lead. Disposed within the lead 300 is a conductor coil 346,which is contained by a lead body 305 having an outer diameter 348. Inone embodiment, lead body 305 is made of silicone rubber having aninterior layer of polytetrafluoroethylene (PTFE), and conductor coil 346is made of titanium (Ti). Hemostasis mechanism 320 is located within thelead lumen 344 at or near the distal end 352 of the lead 300. In analternative embodiment shown at FIG. 3B, hemostasis mechanism 320 islocated within the lead lumen 344 at or near the proximal end 354 of thelead 300. Providing a seal at the proximal end puts the point of dragoutside the vasculature where it can easily be maneuvered and lubricatedas necessary. In a still further embodiment, lead 300 has a firsthemostasis mechanism located at or near its distal end 352 (as shown atFIG. 3A), and a second hemostasis mechanism located at or near proximalend 354 (as shown at FIG. 3B).

[0035] In one embodiment, hemostasis mechanism 320 comprises asubstantially planar membrane. It should be noted that the hemostasismechanism 320 optionally has other configurations other than planar. Inone embodiment, the membrane is normal to the main axis of the lead 300.In one embodiment, the hemostasis mechanism 320 is comprised of ahousing 310 having a polymer membrane 322. Housing 310 is made of anysuitable biocompatible material. Housing 310 may be made of moldedplastic, or a metal such as titanium. The housing may alternatively bemade of silicone rubber or polyurethane, or other biocompatiblematerial. The membrane 322 is made of any suitable biocompatiblematerial. Examples of suitable materials include but are not limited tosilicone rubber, polyurethane, hydrogels and other biocompatibleelastomers.

[0036] Membrane 322 is held within housing 310, in one option, by aninterference fit. Alternatively, membrane 322 is adhesively bonded tohousing 310.

[0037] As shown in FIGS. 3C and 3D, housing 310 optionally comprises anannular recessed area 326 in which membrane 322 is held.

[0038] The hemostasis mechanism 320 is retained within the lead lumen344 as shown in FIG. 3A. For instance, the housing 310 is a tubularmember 312 made of titanium and is laser welded to the lead 300.Alternatively, other attachment methods, such as resistance welding oradhesive bonding, are used. The housing may be attached to the leadproximal to an end of the electrode. Referring to FIG. 3D, housing 310alternatively comprises an indented portion 328 which when inserted inthe distal end of the lead 300 defines a proximally facing annularshoulder 330 which meets the exterior of lead 300.

[0039] In the embodiment shown at FIG. 3B, the hemostasis mechanismcomprises the terminal pin 355 which serves as a housing in whichmembrane 322 is held as described herein with regard to housing 310(FIG. 3A). Suitable materials for the terminal pin 355 include, but arenot limited to, those described herein with regard to housing 310.

[0040] In one embodiment, membrane 322 comprises a cusp valve mechanism324 which allows the passage of a needle 350 or guide wire 350therethrough and prevents the migration of blood into the lead lumen. Inone embodiment, the seal and valve are comprised of silicone rubber orother suitable biocompatible polymer. Variations for the cusp valvemechanism 324 are shown in FIGS. 4-6. FIG. 4 shows a quad cusp valve324A. In an alternative embodiment, valve 324 is a bicusp valve, asshown at 324B of FIG. 5, or a tricusp valve as shown at 324C of FIG. 6.In further embodiments the membrane 322 shown at FIG. 3A comprises acusp valve mechanism as shown at FIGS. 4-6. In further embodiments, thelead shown at FIG. 3B comprises a cusp valve mechanism as shown at FIGS.4-6.

[0041] Referring to FIG. 7, a seal 720 is shown. The seal comprises aremovable disposable mechanism 722 comprising a housing 710 with amembrane 724 housed therein. The housing 710 is attached to the leadbody 702 at the proximal end 754 of the lead 700. The housing 710attaches to the terminal pin 760 of the lead 700.

[0042] The housing 710 of the seal 720 may be made of molded plastic,silicone rubber, or polyurethane. The membrane 724 is attached to andextends across the interior 726 of the housing 710. In one embodiment,membrane 724 is made of a biocompatible polymeric material, such assilicone rubber or polyurethane. In one embodiment, the membrane isintegral with the housing, molded as one piece. The membrane 724 has asmall hole or slit 728 (FIG. 8) to permit penetration with a needle tofill the lead lumen 744 with saline or other suitable sterile solution.Referring to FIG. 8, in one embodiment the membrane has multiple slits730.

[0043] When the needle is withdrawn, the polymer membrane 724 closessufficiently to maintain a hydraulic lock on the fluid in the lumen 744.The guide wire 770, optionally is passed through the membrane 724 andinserted into the lead lumen 744 and the lead 700 is deployed in theusual fashion. In a further option, the lead 700 is deployed using acatheter and/or the guide wire 770. The column of saline, maintained inthe lead lumen 744 by the attached membrane 724, an optional secondmembrane and/or venous pressure, prevents blood from entering the leadlumen 744 and mitigates handling problems due to coagulation of bloodwithin the lead 700.

[0044] In a method of use, a lead 700 is provided, and a seal 720 isattached to the lead 700, for example, by attaching a housing to theterminal pin 760 of lead body 702 at the proximal end of the lead. Aneedle is inserted in the hole or slit 728 of the seal membrane 724 tofill the lead lumen 744 with saline or other suitable sterile solution.Venous pressure maintains the column of fluid therein. The needle iswithdrawn, and the polymer membrane 724 closes sufficiently to maintaina hydraulic lock on the fluid in the lumen 744. The guide wire 770 isoptionally passed through the membrane 724 and inserted into the leadlumen 744. It should be noted that the guide wire 770 can be insertedinto the lead lumen 744 prior to or after the filling of the lumen 744with the sterile solution. The lead 700 is then deployed in the usualfashion. The column of saline is maintained in the lead lumen 744 by theattached membrane 724 and venous pressure and/or an additional distalseal. In one embodiment, lead 700 further comprises a distal hemostasismechanism, as shown at FIG. 3A, and the column of saline is maintainedin the lead lumen 744 between membrane 724 and the membrane of a distalhemostasis mechanism (as shown at 324 of FIG. 3A). The column of salineprevents blood from entering the lead lumen 744 and mitigates handlingproblems due to coagulation of blood. In an alternative embodiment, thelead is disposed in and guided within a guide catheter before, during,or after the fluid is injected into lumen 744.

[0045] An alternative embodiment as shown in FIG. 9 is a lead 800 havinga main lead body portion 802, a lumen 844 and a terminal pin 860. Sealmechanism 820 comprises two grommet style hubs 858 and 862 located ateither end of body 830. Seal mechanism 820 is attached to terminal pin860 by a grommet assembly 858. The grommet assembly 858 is comprised oflocking hub 821 and elastomeric grommet 822 and attaches the sealmechanism 820 to lead terminal pin 860 and seals tightly. The hemostasisvalve provides for passage of a guide wire (not shown) and is comprisedof hub 861 and elastomeric grommet 863. Seal mechanism 820 furthercomprises a side injection port 880 for periodic or continuousintroduction of sterile fluid.

[0046] It is to be understood that the above description is intended tobe illustrative, and not restrictive. Many other embodiments will beapparent to those of skill in the art upon reading and understanding theabove description. For instance, the seal can be used with a variety ofmedical devices. Such a medical device may comprise or require a firstseal at its proximal end and a second seal at its distal end. Althoughthe use of the lead has been described for use in a cardiac pacingsystem, the lead could as well be applied to other types of bodystimulating systems. In addition, the lead could also be applicable tobipolar pacing leads having two separate conductors, and to multipolarpacing leads employing multiple conductor leads. The scope of theinvention should, therefore, be determined with reference to theappended claims, along with the full scope of equivalents to which suchclaims are entitled.

What is claimed is:
 1. An intravenous lead comprising: an elongateflexible lead body made of an electrically insulative material, the leadbody having a proximal end and a distal end; at least one lumenextending through the lead body from the proximal end toward the distalend, the at least one lumen having a first opening through the proximalend and a second opening through the distal end; a conductive memberextending through the lead body from the proximal end toward the distalend of the lead body; at least one electrode electrically coupled to theconductive member; and a hemostasis mechanism comprising a polymermembrane operably coupled with the at least one lumen.
 2. The lead asrecited in claim 1, wherein the hemostasis mechanism is located near thedistal end of the lead.
 3. The lead as recited in claim 2, wherein theelectrode is located near the distal end of the lead body and thehemostasis mechanism is located distal of the electrode.
 4. The lead asrecited in claim 1, wherein the hemostasis mechanism is disposed withinthe lead lumen.
 5. The lead as recited in claim 1, wherein thehemostasis mechanism is attached to and carried by the lead.
 6. The leadas recited in claim 1, wherein the hemostasis mechanism furthercomprises a housing in which the polymer membrane is disposed.
 7. Thelead as recited in claim 6, wherein the housing is tubular.
 8. The leadas recited in claim 6, wherein the housing is comprised of siliconerubber or polyurethane or hydrogel.
 9. The lead as in claim 8, whereinthe housing is adhesively bonded to an interior surface of the lead. 10.The lead as recited in claim 6, wherein the housing is comprised oftitanium.
 11. The lead as recited in claim 10, wherein the housing islaser welded to the lead proximal to an end of the electrode.
 12. Thelead as recited in claim 10, wherein the housing is adhesively bonded tothe lead proximal to an end of the electrode.
 13. The lead as recited inclaim 6, wherein the housing further comprises an indentationconstructed and arranged to mate with the lead body.
 14. The lead asrecited in claim 13, wherein the indentation is located at the proximalend of the housing and defines a proximally facing annular shoulderwhich meets an exterior portion of the distal end of the lead body. 15.The lead as recited in claim 6, wherein the housing comprises an annularrecessed area wherein the polymer membrane is held.
 16. The lead asrecited in claim 6, wherein the polymer membrane is held within thehousing by an interference fit.
 17. The lead as recited in claim 6,wherein the polymer membrane is adhesively bonded within the housing.18. The lead as recited in claim 1, wherein the hemostasis mechanismincludes a valve.
 19. The lead as recited in claim 18, wherein the valveis comprised of silicone.
 20. The lead as recited in claim 19, whereinthe valve is a bicusp valve.
 21. The lead as recited in claim 19,wherein the valve is a tricusp valve.
 22. The lead as recited in claim19, wherein the valve is a quad cusp valve.
 23. The lead as recited inclaim 1, wherein the lumen thereof is filled with a sterile fluid,maintained in the lumen by a hydraulic lock provided by the hemostasismembrane.
 24. The lead as recited in claim 1, wherein the hemostasismechanism is removably attached to the lead and is disposable.
 25. Anintravenous lead comprising: an elongate flexible electricallyinsulative lead body having a proximal end, a distal end, and a lumenextending therethrough, the lumen having a first proximal end openingand a second distal end opening; a conductive member extending throughthe lead body from the proximal end toward the distal end of the leadbody; an electrode electrically coupled to the conductive member; and apolymer membrane operably coupled with the lead lumen at the proximalend of the lead body.
 26. An intravenous lead comprising: an elongateflexible lead body made of an electrically insulative material, the leadbody having a proximal end and a distal end and being adapted forimplantation on or about the left side of the heart, the lead bodyhaving an interior portion defining a lumen extending through the leadbody from the proximal end toward the distal end, the lead body having afirst proximal end opening and a second distal end opening; a conductivemember extending through the lead body from the proximal end toward thedistal end of the lead body; an electrode located near the distal end ofthe lead body, the electrode electrically coupled to the conductivemember; and a hemostasis mechanism operably coupled with the lead andlocated near the proximal end of the lead, the hemostasis mechanismcomprising a polymer membrane.
 27. The lead as recited in claim 26,wherein the hemostasis mechanism is disposed within the lead lumen. 28.The lead as recited in claim 26, wherein the lead is an over-the-wireleft ventricular lead having an atraumatic tip.
 29. The lead as recitedin claim 26, wherein the polymer membrane is comprised of siliconerubber or polyurethane or a hydrogel.
 30. The lead as recited in claim26 further comprising a terminal pin, the hemostasis mechanism attachedto and extending from the terminal pin.
 31. The lead as recited in claim26 further comprising a terminal pin, wherein the hemostasis mechanismis integral with and disposed within the terminal pin.
 32. The lead asrecited in claim 31 further comprising a port, and wherein thehemostasis mechanism further comprises a grommet, the hemostasismechanism being removably connected to the terminal pin by the grommet.33. The lead as recited in claim 26, wherein the polymer membranedefines at least one hole to allow penetration of the membrane with aneedle or a guide wire.
 34. The lead as recited in claim 26, wherein thepolymer membrane defines at least one slit adapted to allow penetrationof the membrane with a needle or a guide wire.
 35. A hemostasismechanism adapted for use with an implantable intravenous lead, thehemostasis mechanism comprising a tubular housing having a polymermembrane located therein.
 36. The hemostasis mechanism of claim 35,wherein the membrane comprises a valve.
 37. The hemostasis mechanism ofclaim 35, wherein the polymer membrane is disposed at the proximal endof the lead body.
 38. A method comprising: providing an over-the-wireleft ventricular lead comprising a lead body having a proximal end, adistal end and a terminal pin at the proximal end thereof, the lead bodyhaving an interior portion defining a lumen therethrough; providing ahemostasis mechanism comprising a housing with a polymer membranetherein, the polymer membrane defining at least one aperture for aneedle or guide wire to penetrate the polymer membrane; attaching thehemostasis mechanism to the lead by attaching the housing to theterminal pin; inserting a needle in the at least one aperture of themembrane and filling the lead lumen with a sterile fluid; withdrawingthe needle from the membrane, whereby the polymer membrane closessufficiently to maintain a hydraulic lock on the fluid in the lumen;passing a guide wire through the membrane and inserting the guide wireinto the lead lumen; and deploying the lead, whereby the column ofsaline is maintained in the lead lumen by the membrane, the column ofsterile fluid preventing blood from entering the lead lumen.
 39. Themethod of claim 38, wherein deploying the lead includes deploying thelead on the left side of a heart.